The proposed research program is designed to study the biochemical nature of the lesion induced by nitrogen dioxide in alveolar macrophages. The following topics will be investigated: THE EFFECTS OF INTROGEN DIOXIDE ON BIOCHEMICAL ACTIVITIES OF ALVEOLAR MACROPHAGES. The lipid composition of cell membranes isolated from alveolar macrophages obtained from normal rabbits and rabbits exposed to NO2 will be compared by extracting, separating and quantifying the various lipid classes. Proteins extracted from isolated membranes will be analyzed by conventional acrylamide gel electrophoresis and by isolectric focusing in acrylamide gel. The effect of NO2 on the synthesis and turnover of lipids, proteins and RNA will be investigated employing the appropriate radioactive substrates. THE EFFECT OF NO2 ON THE FUNCTION OF ALEOLAR MACROPHAGES The comparative effects onf NO2 on pinocytosis, phagocytosis and motility will be studied employing standard techniques. The effect of NO2 on membrane integrity will be studied employing the principle of enzyme (LDH) leakage. EFFECT OF NO2 ON VIRUS-CELL INTERACTION